Nozzle Appliance for a Jet Pump and Jet Pump

ABSTRACT

The present invention relates to a nozzle appliance for a jet pump, comprising a driving nozzle and a first suction nozzle, wherein the first suction nozzle is arranged radially outward of the driving nozzle and wherein the nozzle appliance is designed such that a fluid flow through the driving nozzle drives a fluid flow through the first suction nozzle. The invention also relates to a jet pump comprising a corresponding nozzle appliance.

INTRODUCTION

The present disclosure relates to a nozzle appliance for a jet pump, including a driving nozzle and a first suction nozzle. The disclosure also relates to a jet pump including a corresponding nozzle appliance.

Jet pumps are used for generating a secondary fluid flow by means of a primary driving fluid flow. The primary driving fluid is accelerated by means of e.g. a pump and guided such that it comes into contact with a secondary fluid. A velocity and pressure gradient between the two fluids ensures that the second fluid is accelerated by the first fluid flow. Therefore, in jet pumps, the second fluid flow is driven by the first fluid flow.

Jet pumps may be designed as single stage or multiple-stage jet pumps including a plurality of pump stages and nozzles. A disadvantage of jet pumps is their low efficiency resulting from the mixing of a high velocity jet of the primary driving fluid with a nearly stagnant secondary fluid.

SUMMARY

One object of the present disclosure is to provide an improved jet pump and an improved jet pump nozzle geometry, which exhibit superior efficiencies compared to known jet pumps and jet pump nozzle geometries.

According to an embodiment, a nozzle appliance for a jet pump is provided, said nozzle appliance including a driving nozzle and a first suction nozzle, wherein the first suction nozzle is arranged radially outward of the driving nozzle and wherein the nozzle appliance is designed such that a fluid flow through the driving nozzle drives a fluid flow through the first suction nozzle. In an embodiment, a driving nozzle outlet may be situated close enough to a first suction nozzle outlet such that the low pressure and high velocity fluid flow of the driving nozzle may interact with the fluid of the first suction nozzle.

The first suction nozzle may be positioned such that the shear stress at the interface between the jet and the suction mass or the fluid flow through the driving nozzle and the fluid flow through the first or further suction nozzles is reduced. This is related to the fact that the above-defined shear stress is the product of fluid viscosity and the velocity gradient. The latter may be very large in jet pumps known from the art. High shear stresses lead to the generation of turbulences, which in return lead to dissipation of primary energy, which is the reason for the low efficiency of known jet pumps. The jet pump and nozzle appliance in an embodiment provide for enhanced jet pump efficiency, as the shear stresses are reduced when the mixing of the two or more mass flows or fluid flows is induced.

In an embodiment, the nozzle appliance can be designed such that the first suction nozzle is arranged concentrically around the driving nozzle and/or that the first suction nozzle comprises an axisymmetric volume, such as a toroidal volume. The driving nozzle and/or the first suction nozzle may include nozzle wall sections, which feature rotational symmetry, in particular around a central axis of one of the nozzles or of both of the nozzles.

In another embodiment, the nozzle appliance can be designed such that a first mixing tube is provided downstream of the driving nozzle and the first suction nozzle. The first mixing tube may be connected to an outside wall of the first suction nozzle. In particular, the first mixing tube and the outside wall of the first suction nozzle may be made from one piece. The first mixing tube, the driving nozzle and the first suction nozzle may be arranged coaxially to each other.

In an embodiment, the nozzle appliance can be designed such that the first mixing tube includes a first diffusor stage at the downstream end of the first mixing tube. The first diffusor stage may feature a larger cross-sectional area than a section of the first mixing tube which is positioned further upstream of the first diffusor stage. The first diffusor stage of the first mixing tube may be arranged concentrically to other portions of the first mixing tube and/or the driving nozzle and/or the first suction nozzle.

In another embodiment, the nozzle appliance can be designed such that a second suction nozzle is arranged downstream of the first mixing tube, wherein the nozzle appliance is designed such that a fluid flow through the first mixing tube drives a fluid through the second suction nozzle and/or wherein the second suction nozzle is arranged concentrically around the first mixing tube and/or wherein the second suction nozzle comprises an axisymmetric volume. The design and functioning of the second suction nozzle may comprise features such as the ones described with respect to the first suction nozzle where applicable.

In particular, the second suction nozzle may be located close enough to the outlet of the first mixing tube such that the low pressure and high velocity fluid flow of the first mixing tube may interact with the fluid of the second suction nozzle. The second suction nozzle may be positioned such that the shear stress at the interface between the jet and the suction mass or the fluid flow through the first mixing tube and the fluid flow through the second suction nozzle is reduced.

In an embodiment, the nozzle appliance can be designed such that a second mixing tube is provided downstream of the first mixing tube and the second suction nozzle. The second mixing tube may be connected to an outside wall of the second suction nozzle. In particular, the second mixing tube and the outside wall of the second suction nozzle may be made from one piece. The second mixing tube, the first mixing tube, the driving nozzle and/or the first and second suction nozzles may be arranged coaxially to each other.

In an embodiment, the nozzle appliance can be designed such that the second mixing tube includes a second diffusor stage at the downstream end of the second mixing tube. The second diffusor stage may feature a larger cross-sectional area than a section of the second mixing tube which is positioned further upstream of the second diffusor stage. The second diffusor stage may be arranged concentrically to other portions of the second mixing tube and/or the driving nozzle and/or the first and/or second suction nozzle.

In an embodiment, the nozzle appliance can be designed such that a first fluid flows through the driving nozzle and a second fluid flows through the first and/or the second suction nozzle, wherein the first and second fluids are the same kinds of fluids or wherein the first and second fluids are different kinds of fluids. The first fluid flowing through the driving nozzle may be regarded as the driving fluid. The first and second fluid may be provided from the same fluid source or from different and separated fluid sources.

In an embodiment, the nozzle appliance can be designed such that the first fluid is a gas and the second fluid is a gas and/or that the second fluid is a liquid. In general, the present nozzle design may be used with any suitable combination of liquids and/or gases. In cases in which a gas is used as one or both of the fluids, air, fuel vapours, combustions gases and mixtures thereof may be chosen as either of the fluids.

An embodiment is also directed at a jet pump including at least one nozzle appliance. The term jet pump may be understood to comprise further components in addition to the nozzle appliance. Such further components may include a power source, a pressure source, a control device, electronic connections, fluid connections, one or more fluid sources and/or fluid conduits.

BRIEF DESCRIPTION OF THE FIGURES

Further details and advantages of the invention are described with reference to the embodiments shown in the figures.

FIG. 1 : nozzle appliance comprising one driving nozzle and two suction nozzles;

FIGS. 2 a, 2 b : schematic view of a nozzle appliance according to the state of the art; and

FIGS. 3 a, 3 b : schematic view of a nozzle appliance according to an embodiment.

DETAILED DESCRIPTION

FIG. 1 shows a nozzle appliance for a jet pump. The term jet pump may be understood in a broad sense and may comprise any further additional components other than the actual nozzle geometry shown in FIG. 1 . The nozzle appliance comprises a driving nozzle 10 and a first suction nozzle 1, wherein the first suction nozzle 1 is arranged radially outward of the driving nozzle 10 and wherein the nozzle appliance is designed such that a fluid flow through the driving nozzle 10 drives a fluid through the first suction nozzle 1. The nozzle appliance may be arranged around a centreline C. In particular, the nozzle appliance may be at least partially symmetrical about centreline C.

The first suction nozzle 1 may be arranged concentrically around the driving nozzle 10. The driving nozzle 10 may have a circular cross section and comprise cylindrical conduit portions. Alternatively or additionally, the driving nozzle 10 may comprise non-cylindrical conduit portions. The first suction nozzle 1 may comprise an axisymmetric volume or axisymmetric conduit portions. The conduit portions of the driving nozzle 10 may be positioned at least partially within the conduit portions of the first suction nozzle 1. In these cases, the nozzle appliance may exhibit rotational symmetry around centreline C at least at some positions along the centreline C.

Alternatively, the nozzle appliance may exhibit reflectional symmetry about a plane which comprises centreline C and which is perpendicular to the plane of projection of FIG. 1 . In this case, the suction nozzle 1 and the driving nozzle 10 may comprise e.g. cuboid or near conduit portions. Furthermore, the nozzle appliance may not exhibit reflectional symmetry about the above defined plane but may still comprise conduit portions of exclusively or at least partially cuboid geometries. The term conduit portion may be presently understood to refer to conduit portions, which are bound by solid walls in a radial direction. The solid walls may surround the conduit portions completely in a circumferential direction of the conduit portions.

The conduit portions of the driving nozzle 10 and the first suction nozzle 1 may be at least partially separated by a first wall 11. The first wall 11 may comprise a conical portion and at least one cylindrical portion connected directly to the conical portion.

The right end or downstream end of the first wall 11 may be regarded as the exit portion of the driving nozzle 10, in which the first fluid of the driving nozzle 10 meets the second fluid of the first suction nozzle 1 and the two fluids interact with each other, such that the second fluid is driven by the first fluid. The inside of the first wall 11 may surround the driving nozzle 10 completely and therefore on its own define the cross-section area and shape of the driving nozzle 10. The outside of the first wall 11 may define the inside boundary of the first suction nozzle 1. The inside and outside of the first wall 11 may comprise surfaces which are parallel or nearly parallel to each other. In particular, the first wall 11 may comprise at least one cylindrical portion or a portion with constant cross-sectional area along the flow direction. This applies in particular to the portion of the first wall 11 which is the furthest downstream portion or close to the furthest downstream portion of the first wall 11. This close alignment of these two sides of the first 11 wall ensures that the streamlines of the flow through the driving nozzle 10 and the streamlines of the flow through the first suction nozzle 1 are parallel or near parallel to each other when flowing together or meeting each other.

Downstream of the exit portion of the driving nozzle 10 a first mixing tube 3 is provided. The fluid flow direction is indicated by the three arrows to the left and above the nozzle appliance. Around and close to the centreline C, the general flow direction in FIG. 1 is from left to right. Downstream positions of components are therefore to be found on the right sides of the components of the nozzle appliance in FIG. 1 .

The first mixing tube 3 is hence provided downstream of the driving nozzle 10 and the first suction nozzle 1. The diameter or cross-sectional area of the mixing tube 3 may be selected such that it may accommodate the combined volume flow of the driving nozzle 10 and the first suction nozzle 1.

The first mixing tube 3 may be bound by a second wall 32 and/or the first mixing tube 3 may comprise a partially or entirely cylindrical conduit portion. The length of the first mixing tube 3 may be selected to be 2 to 5 times the width or the diameter of the mixing tube 3. In particular, the length of the mixing tube 3 may be selected to be 2.5 to 4 times the width or the diameter of the mixing tube 3.

The first mixing tube 3 may be designed such that it comprises a first diffusor stage 31 at the downstream end of the first mixing tube 3. The first diffusor stage 31 may be of a greater cross-sectional area, diameter or width than other, in particular upstream, portions of the first mixing tube 3. The first diffusor stage 31 may be the most downstream portion or may be close to the most downstream portion of the first mixing tube 3. The first mixing tube 3 and the first diffusor stage 31 may be formed integrally by the second wall 32.

The first diffusor stage 31 may be close to or may be part of a second suction nozzle 2, which is arranged downstream of the first mixing tube 3, wherein the nozzle appliance is designed such that a fluid flow through the first mixing tube 3 drives a fluid through the second suction nozzle 2 and/or wherein the second suction nozzle 2 is arranged concentrically around the first mixing tube 3 and/or wherein the second suction nozzle 2 comprises an axisymmetric volume, bound by inner and outer walls.

As shown in the embodiment of FIG. 1 , the present nozzle appliance may be a one or more stage nozzle appliance, comprising a multitude of suction nozzles 1, 2 and/or driving nozzles 10. Hence, the most downstream portion of the first mixing tube 3, in particular the exit portion of the first mixing tube 3 may be regarded as another driving nozzle or as a part of another driving nozzle for driving fluid through the second suction nozzle 2.

The geometry of the second suction nozzle 2 may correspond to the geometry of the first suction nozzle 1 in that it may exhibit rotational symmetry around centreline C or reflective symmetry in analogy to the reflective symmetry of the first suction nozzle 1 described above. Alternatively, a non-symmetric embodiment is also possible as described above. Furthermore, the walls bounding the second suction nozzle 2, i.e. the second wall 32 on the inside of the second suction nozzle 2 and another wall on the outside of the second suction nozzle 2 may be oriented such that they align the flow through the second suction nozzle 2 closely to the flow through the first mixing tube 3. In particular, the second suction nozzle 2 may be provided such that the velocity vectors of the fluid flow through the second suction nozzle 2 approach the velocity vectors of the fluid flow through the first mixing tube 3 in direction and magnitude. The bounding walls of the second suction nozzle 2 may be therefore parallel and/or angled to the flow direction through the mixing tube 3 such that the flow through the first mixing tube 3 and the flow through the second suction nozzle 2 mix together with only minimal losses.

A second mixing tube 4 may be provided downstream of the first mixing tube 3 and the second suction nozzle 2. The second mixing tube 4 may comprise cylindrical conduit portions and/or a second diffusor stage 41 at the downstream end of the second mixing tube 4. The downstream end of the second mixing tube 4 may be connected or connectable to a fluid conduit.

During operation of the nozzle appliance, the driving nozzle 10 is flowed through by a first fluid and the first suction nozzle 1 and/or the second suction nozzle 2 are flowed through by a second fluid, wherein the first and second fluids are the same kinds of fluids or wherein the first and second fluids are different kinds of fluids. The first fluid of the driving nozzle 10 drives the fluids flowing through the suction nozzles 1, 2 and the fluids may be gases and/or liquids.

The fist suction nozzle 1, or the two or more suction nozzles 1, 2 may be annular or near annular nozzles surrounding the circular driving nozzle 10 or surrounding further driving nozzles at least partially. The driving nozzle 10 may be surrounded concentrically or in a different way. The driving nozzle 10 may be a driving air nozzle. The nozzle appliance may be used together with a turbo charger of a combustion engine. In this case, the nozzle appliance may be regarded as part of a jet pump for pumping gases from e.g. a fuel tank and into the combustion engine.

The nozzles of certain embodiments of the present disclosure may be designed such that the flow velocities and/or the flow directions of neighbouring nozzles are as similar as possible. In particular, the nozzles may be designed such that the flow directions and/or velocities of the first fluid flow exiting the driving nozzle 10 are as similar as possible to the second fluid flow exiting the first and/or second suction nozzles 1, 2.

The present nozzle appliance and corresponding jet pumps in effect provide at least one additional suction nozzle 1, 2, increasing the flow velocity of the suction flow before it mixes with the driving flow. The additional suctions nozzle 1, 2 effectively reduces the generation of turbulences during mixing of the at least two fluid flows, i.e. the first and second fluid flows. As a result, power and efficiency of the pump are increased.

Power is supplied to corresponding jet pumps in form of a driving mass flow, which is accelerated in a driving nozzle and which correspondingly generates a fluid jet of high velocity and low pressures. The emerging low pressure is utilized to draw a suction mass flow into the pump or nozzle appliance, which mixes with the driving flow i.e. the first fluid flow. Driving mass flux or first fluid flow and suction mass flux or second fluid flow leave the pump or nozzle appliance after passing one or more diffusor stages 31, 41, which increase the pressure of the flow.

One advantage of jet pumps, per certain embodiments, is their simple design with no need for moving parts. Major disadvantages may include the low efficiency of such pumps resulting from the mixing of a high velocity jet with a nearly stagnant fluid.

FIG. 2 a shows a schematic view of a typical jet pump flow configuration as known from the art. FIG. 2 b shows a simplified representation of the corresponding fluid flow. As shown in FIG. 2 a , a jet of high velocity is generated by a driving nozzle 10, which draws in the suction mass flow, which typically has a very low velocity.

FIG. 2 b is an idealized representation of a typical jet pump flow. The low velocity suction mass flow is indicated by the short horizontal arrows. It mixes with the high velocity jet indicated by long horizontal arrows. The high velocity gradient shown leads to high shear stresses. The flow shown in FIG. 2 b only accounts for the flow component in the direction of the jet, i.e. the horizontal direction.

The shear stress _(T) at the interface between jet and suction mass flow or between the first and second fluid flow, respectively, increases with the velocity gradient of the corresponding fluid flow. The latter is usually very large due to the high difference in the velocities of the two fluid flows. High shear stresses lead to the generation of turbulences, which in return lead to dissipation of primary energy, which is the reason for the low efficiency of jet pumps. A more efficient jet pump requires a reduction of the shear stress induced by the mixing of the two mass flows. As the jet velocity is dictated by the necessary pumping pressure, the only way to reduce the shear stress at the interface is by increasing the flow velocity of the suction flow in direction of the jet flow.

FIGS. 3 a and 3 b show a jet pump flow configuration in which the suction flow is accelerated before mixing with the jet, thereby decreasing the velocity gradient. This reduces the shear stresses and therefore the amount of generated turbulences and dissipated energy. As a result, less energy is lost, and the jet pump is more efficient. In FIG. 3 a , the jet pump or nozzle appliance comprises the driving nozzle 10 and the first suction nozzle 1 for the suction flow. FIG. 3 b shows an idealized representation of the corresponding flow. The suction flow velocity is indicated by the shorter horizontal arrows and the jet flow velocity is indicated by the longer horizontal arrows. As can be seen, the difference in length and therefore velocity is smaller than in the situation shown in FIG. 2 b . Therefore, the shear stress is reduced. As before, the flow shown in FIG. 3 b only accounts for the flow component in the direction of the jet, i.e. the horizontal direction. The suction nozzles 1, 2 may be designed to direct the second fluid flow such that it approaches the first fluid flow in a parallel direction to it or at a very small angle. In order to achieve this effect, the suction nozzles 1, 2 may comprise correspondingly angled boundaries.

The present disclosure, per certain embodiments, is of particular use for the ventilation of crankcases and fuel tanks of vehicles. Due to blow-by and fuel evaporation, these components need to be ventilated by use of corresponding jet pumps in order to achieve current emission regulations. Here, the air provided to a combustion engine may be used as a driving fluid or first fluid. The air provided may be compressed air e.g. from a turbocharger or a compressor. The present disclosure, per certain embodiments, provides highly performant means for ventilating these components at idle engine and full throttle operation resulting in low and high driving pressures. At the same time, the present disclosure, per certain embodiments, provides for jet pumps with low consumption of driving air or driving fluid at full throttle of the engine.

As used herein, the terms “general,” “generally,” and “approximately” are intended to account for the inherent degree of variance and imprecision that is often attributed to, and often accompanies, any design and manufacturing process, including engineering tolerances, and without deviation from the relevant functionality and intended outcome, such that mathematical precision and exactitude is not implied and, in some instances, is not possible.

The invention is not limited to any of the above-described embodiments or features. The invention may comprise various additions to or modification of the described embodiments.

All of the features and advantages arising from the claims, the description and the drawings, including structural details, spatial arrangements and procedural steps, can be essential to the invention both, individually and in the most varied of combinations.

All the features and advantages, including structural details, spatial arrangements and method steps, which follow from the claims, the description and the drawing can be fundamental to the invention both on their own and in different combinations. It is to be understood that the foregoing is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

As used in this specification and claims, the terms “for example,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.

List of reference numerals 1 first suction nozzle 2 second suction nozzle 3 first mixing tube 4 second mixing tube 10 driving nozzle 11 first wall 31 first diffusor stage 32 second wall 41 second diffusor stage C centreline 

1. Nozzle appliance for a jet pump, comprising a driving nozzle and a first suction nozzle, wherein the first suction nozzle is arranged radially outward of the driving nozzle and wherein the nozzle appliance is designed such that a fluid flow through the driving nozzle drives a fluid through the first suction nozzle.
 2. Nozzle appliance according to claim 1, wherein the first suction nozzle is arranged concentrically around the driving nozzle.
 3. Nozzle appliance according to claim 1, wherein a first mixing tube is provided downstream of the driving nozzle and the first suction nozzle.
 4. Nozzle appliance according to claim 3, wherein the first mixing tube comprises a first diffusor stage at the downstream end of the first mixing tube.
 5. Nozzle appliance according to claim 3, wherein a second suction nozzle is arranged downstream of the first mixing tube, wherein the nozzle appliance is designed such that a fluid flow through the first mixing tube drives a fluid through the second suction nozzle.
 6. Nozzle appliance according to claim 5, wherein a second mixing tube is provided downstream of the first mixing tube and the second suction nozzle.
 7. Nozzle appliance according to claim 6, wherein the second mixing tube (4) comprises a second diffusor stage at the downstream end of the second mixing tube.
 8. Nozzle appliance according to claim 5, wherein a first fluid flows through the driving nozzle and a second fluid flows through the first and/or the second suction nozzle, wherein the first and second fluids are the same kinds of fluids or wherein the first and second fluids are different kinds of fluids.
 9. Nozzle appliance according to claim 8, wherein the first fluid is a gas and the second fluid is a gas and/or the second fluid is a liquid.
 10. Jet pump comprising at least one nozzle appliance according to claim
 1. 11. Nozzle appliance according to claim 2, wherein the first suction nozzle comprises an axisymmetric volume.
 12. Nozzle appliance according to claim 1, wherein the first suction nozzle comprises an axisymmetric volume.
 13. Nozzle appliance according to claim 5, wherein the second suction nozzle is arranged concentrically around the first mixing tube.
 14. Nozzle appliance according to claim 5, wherein the second suction nozzle comprises an axisymmetric volume.
 15. Nozzle appliance according to claim 13, wherein the second suction nozzle comprises an axisymmetric volume. 